element-type cx cy dx dy r a
\end{verbatim}
The first entry defines the type of the element, either
-\rtfsp\texttt{rectangle}, \texttt{}, \texttt{triangle},
+\rtfsp\texttt{rectangle}, \texttt{ellipse}, \texttt{triangle},
\rtfsp\texttt{sector}, or \texttt{segment}. \texttt{cx},
\rtfsp\texttt{cy}, \texttt{dx} and \texttt{dy} have different
meanings depending on the element type.
\emph{phantom diameter}. Remember, as mentioned above, the
phantom dimensions are also padded by 1\%.
-The other important geometry variables for scanning objects are the
-\emph{view ratio}, \emph{scan ratio}, and \emph{focal length ratio}.
-These variables are all input into \ctsim\ in terms of ratios rather
-than absolute values.
+The other important geometry variables for scanning phantoms are
+the \emph{view diameter}, \emph{scan diameter}, and \emph{focal
+length}. These variables are all input into \ctsim\ in terms of
+ratios rather than absolute values.
\subsubsection{Phantom Diameter}
\begin{figure}
experimental purposes, it may be desirable to scan an area either
larger or smaller than the \emph{view diameter}. Thus, the concept
of \emph{scan ratio}, \latexonly{$s_r$,}\latexignore{\emph{SR},}
-is born. The scan diameter
+is arises. The scan diameter
\latexonly{$s_d$}\latexignore{\emph{Sd}} is the diameter over
which x-rays are collected and is defined as \latexonly{$$s_d =
v_d s_r$$}\latexignore{\\$$\emph{Sd = Vd x SR}$$\\} By default and
\subsubsection{Detector Array Size}
In general, you do not need to be concerned with the detector
-array size. It is automatically calculated by \ctsim. For those
-interested, this section explains how the detector array size is
-calculated.
+array size. It is automatically calculated by \ctsim. For the
+particularly interested, this section explains how the detector
+array size is calculated.
For parallel geometry, the detector length is equal to the scan
diameter.